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Morning all
Mk2 son is building a 1.8 silvertop zetec engined sapphire
Hes got a misfire
Question- is it possible for the coil pack to stop working on one cylinder, or do they usually give up altogether? We’ about to start investigating compression etc, but plugs and leads are new
Yeah I know that just because parts are new, it doesn’t necessarily mean they’re good, but trying to cover all ideas
TIA
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Yes single coil packs can be faulty.
You could move one known good coil pack to the cylinder that has the misfire and the coil pack from that cylinder to where the other came from.
If the misfire moves with the coil pack you've identified a faulty coil pack but if the misfire remains with the original cylinder you can then check for correct supply voltage, earth path/trigger signal at the wiring.
If that is all good then move on to a compression check.
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Last Edit: Nov 28, 2020 8:56:04 GMT by asdajnr
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Rich
Club Retro Rides Member
Posts: 6,237 
Club RR Member Number: 160
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Ford zetec misfire queryRich
@foxmcintyre
Club Retro Rides Member 160
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Yes single coil packs can be faulty. You could move one known good coil pack to the cylinder that has the misfire and the coil pack from that cylinder to where the other came from. If the misfire moves with the coil pack you've identified a faulty coil pack but if the misfire remains with the original cylinder you can then check for correct supply voltage, earth path/trigger signal at the wiring. If that is all good then move on to a compression check. I think it’s a single coil block on wasted spark. In which case swap a plug lead, so if the miss is on one or four, swap those at the coil and see if the misfire moves, and the same if it’s on two or three. |
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Nov 28, 2020 13:23:00 GMT
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You’re right rich, it is single pack, thanks we’ll try that |
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Dez
Club Retro Rides Member
And I won't sit down. And I won't shut up. And most of all I will not grow up.
Posts: 11,712
Club RR Member Number: 34
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Ford zetec misfire queryDez
@dez
Club Retro Rides Member 34
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Nov 28, 2020 15:49:29 GMT
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One thing I found with zetec coil packs is they’re really picky about how well they’re earthed. Make sure it’s got a decent earth strap or a good earth path through the bracketry as this can cause misfires too.
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Nov 28, 2020 15:50:31 GMT
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They're also prone to the wires breaking where they come out of the plug.
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mk2cossie
Club Retro Rides Member
Posts: 2,948
Club RR Member Number: 77
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Ford zetec misfire querymk2cossie
@mk2cossie
Club Retro Rides Member 77
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Nov 28, 2020 20:58:23 GMT
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What style of coil pack is it? As Ford now supply a modified replacement coil pack for a lot of models which is significantly beefier than most old ones  |
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What style of coil pack is it? As Ford now supply a modified replacement coil pack for a lot of models which is significantly beefier than most old ones Itll be the standard one from the ‘96 escort i took the engine from about 11 years ago when I scrapped it, but it’s done nothing since then |
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Have you checked if there is a decent spark using an old spark plug?
If there is I'd move onto compression then injectors etc.
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Wasted spark systems, if that is what this is, usually cause a 2 cylinder misfire. Though you didn’t say whether it’s an intermittent mid or a dead cylinder.
If the engine has been sat 11 years then a stuck/blocked injector or hanging valve are both good candidates
Nick
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1967 Triumph Vitesse convertible (old friend)
1996 Audi A6 2.5 TDI Avant (still durability testing)
1972 GT6 Mk3 (Restored after loong rest & getting the hang of being a car again)
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Well its not electrical, good spark on all four
So that leaves injectors or compression, it used to run fine, so I suppose it could be stuck rings, but since its outside ill be waiting for the rain to stop before further investigation
Thrilling isnt it
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If he has enough time to leave it sitting for a bit I'd be tempted to pour some diesel down the bores and let it sit.
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If he has enough time to leave it sitting for a bit I'd be tempted to pour some diesel down the bores and let it sit. If the compression is low enough to cause a miss, it’s low enough to hear when cranking over. It’s also much more likely to be a stuck valve as the rings have to be really grotty for the compression to be low enough to cause an actual miss. If the injectors have been sat with fuel dregs in for 11 years the bigger surprise is that 3 are still working! Nick |
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1967 Triumph Vitesse convertible (old friend)
1996 Audi A6 2.5 TDI Avant (still durability testing)
1972 GT6 Mk3 (Restored after loong rest & getting the hang of being a car again)
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I'd also go for the injectors as a first place too look after 11 years the residual fuel will turn to goo, if you know which cylinder is missing swap the injectors and see if the misfire goes with it.
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It starts pretty readily, so I'm not convinced it's compression, going to check the injectors
They’re not expensive for these, so might end up just bunging another set on
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Dec 19, 2020 15:56:11 GMT
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Right, part 2
Good spark on all 4 (did I already say that?) still misfiring, changed injectors still misfire
Not been able to check compression because zetec, plugs are too far into head for my compression tester to reach
It’s a modified rs1800 fiesta loom, each injector plug has a brown with tracer and black wire, but we cant find a wiring diagram for that loom
Anyone know which colour is which injector?
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